Vizio VF551XVT LED LCD HDTV

Published on Monday, 11 January 2010 19:52

Pete Putman

16 Comments

As prices of flat-screen HDTVs continue to plunge, you can point the finger at one company in particular for influencing that trend: Vizio. The aggressive discounter has become a dominant player in LCD HDTV sales, capturing the #1 position on more than one occasion and sticking it to established stalwarts like Sharp, Sony, and Samsung.

First getting started with wholesale clubs like Costco and Sam’s Club, Vizio is also in Wal-Mart and Sears. Taking a page from Samsung, the company advertises extensively during the fall football season. And its lineup of TVs covers all of the bases from a $200 19” LCD model to three 55-inch 1080p LCD sets, the most expensive of which is $2,199 and the subject of this review.

Vizio’s VF551XVT will naturally get lots of attention for its super-low price. The fact that it has an LED backlight and incorporates 240Hz motion processing will only attract more attention. And yet, its narrow viewing angle impaired the viewing experience for me.

Figure 1. Vizio’s VF551XVT is the company’s first LCD TV to use an LED backlight.

OUT OF THE BOX

The VF551XVT comes ready to play, out of the box. Simply unpack it and find a suitable flat surface to set it on – the stand is attached. (Vizio also offers a white glove delivery service for a few extra dollars.)

You’ll get plenty of inputs, as is usual with Vizio. The rear panel contains four HDMI 1.3 jacks, one of which also comes with analog audio inputs for connection to older DVI-equipped DVD players and set-top boxes. There’s also a component video input, a PC input (VGA jack), and one each composite and S-video jacks with analog audio.

On the left side, you’ll find a fifth HDMI 1.3 connector, plus another component video input and a second composite video input. (Question: Why are manufacturers of large 1080p LCD HDTVs including composite video jacks at all, let alone two of them?)

Figure 2. You won’t lack for connections on this TV. How do five HDMI inputs sound?

An optical Toslink jack on the rear panel provides a digital audio hook-up to an external home theater receiver, and there are also analog stereo audio output jacks. For TV viewing, the VF551XVT includes a single F connector, which can pull in either terrestrial (ATSC) digital and analog TV stations, or analog/digital cable channels that haven’t been encrypted.

Vizio has also included an USB port for listening to and watching a wide range of portable media files, including MPEG4 (H.264 AVC), Windows Media 7/8/9, MPEG2, AAC, MP3, and JPEG still images. These external flash drive connections are actually quite popular with consumer, particularly for showing home video or digital photographs!

REMOTE AND MENUS

The supplied remote is a great design, with just the right number of buttons that are large enough to operated without reading glasses. It’s also backlit for darkened rooms. You can select banks of inputs by pressing one of four smaller buttons and then toggling through the choices.

Figure 3. The remote is stylish and well laid out.

The menus are well designed, and navigation through them is quick and easy. For the average viewer, you can select one of nine factory picture presets, all of which can be altered. The differences between the sports-themed presets (Football, Golf, Basketball, and Baseball) are almost insignificant, and you have to wonder why Vizio included so many. The good news is, you can tweak all of them to your heart’s content.

Vizio has also incorporated a host of image processing adjustments under the Advanced Video sub-menu. For more detailed calibrations, Vizio has included four color temperature presets (Normal, Custom, Cool, and Computer), plus red, green, and blue contrast and brightness adjustments.

Heads up – if you want to calibrate the TV (or have someone else do an ISF calibration), you’ll need to leave all of the image enhancements off, particularly the color enhancement, adaptive luma, and smart dimming – a feature that adjusts the brightness of the image dynamically to improve blacks by controlling blocks of LEDs.

The white LEDs – 960 of them, divided into 80 blocks – can provide instantaneous dimming to lower black levels in dark scenes while raising them in bright scenes. In theory, that should result in very high contrast ratios…except that highlights are also dimmed as black levels drop, and that makes for some screwy gamma curves.

120Hz LCD TVs are pretty commonplace now, but their effectiveness in reducing motion blur is debatable. Vizio has moved to a 240Hz system, deriving that frame rate by a combination of partial black frame insertion with a scanning (switching) LED backlight. The control for it is labeled Smooth Motion, and has three settings, plus off.

The audio menu is pretty conventional, but does include a handy lip sync adjustment to correct for audio latency errors – a technical problem you’d think would be rare, but pops up more often than it should. SRS TruSurround sound is also included in the VF551XVT, as is SRS’ TruVolume peak limiter. This latter processor keeps you from being blasted out of your chair by a loud commercial after a relatively quiet program.

ON THE TEST BENCH

I found most of the factory picture settings for the VF551XVT to be way too bright, and a quick check with my calibration tools confirmed that observation. Factory set brightness modes are in the range of 430 nits, or 126 foot-Lamberts. (That’s tanning lamp territory!) For everyday viewing, you’ll want to crank back the contrast, brightness, and backlight setting considerably to avoid eyestrain. Yes Virginia, there is such a thing as too much brightness…

I selected Normal mode and calibrated the VF551VXT for best dynamic range, a job that is not at all easy since you have both an adjustable backlight and contrast and brightness settings to deal with. Eventually I chose a peak brightness value of 140 nits, which works out to a very-bright 41 foot-Lamberts. The backlight was set right in the middle, at 50.

As I mentioned earlier, all image enhancement or processing settings were turned off for calibration. Even so, it was quite a job to determine what “black” was! With the backlight set too high, “black” is a pretty washed-out gray. Set it too low, and overall image brightness suffers. (After calibration, the lowest average black level I measured was .265 nits, which is about three times higher than a typical plasma TV.)

My initial calibrations resulted in some extremely steep gamma curves measuring close to 3.0. Normal video gamma would be between 2.2 and 2.3, so I had to play with both the brightness control and backlight to find that elusive combination of low grays that gave me a normal gamma, but preserved shadow detail. After several tries, I produced the somewhat inconsistent gamma curve seen in figure 4 – it averages out to a 2.3 value.

Figure 4. Here’s the final gamma curve for the VF551XVT. It’s a little bumpy.

Contrast measurements were decent. Using a 16-block checkerboard, I measured average (ANSI) contrast at 481:1 and peak contrast within the same test pattern at 589:1. A sequential contrast measurement came to 528:1 – lower than the peak contrast ratio. How is that possible?

Simple – the VF551XVT’s brightness uniformity varies noticeably across a full white test pattern. Taking nine measurements across the screen, you’ll se a variation of about 8% from the highest to lowest reading. Go into the corners, and the difference is as much as 15%.

Color temperature also shifts by quite a bit over that same full white screen. I measured a shift of 634 Kelvin from lowest to highest readings, and that was in two adjacent screen areas. Measured at the center, the VF551XVT tracks a tight grayscale around 6500 Kelvin, as seen in Figure 5.

Now, about the visual “flaw” I mentioned at the start of this review: Like all LCD TVs, the VF551XVT has issues with brightness uniformity over wide viewing angles. On this TV, you will notice that black levels on different parts of the screen increase dramatically with small changes in horizontal and vertical viewing angles, and that’s not good.

The variation in black levels isn’t consistent across the screen. I noticed this immediately while displaying a small area white window test pattern. As I moved my chair left to right from the dead-center “sweet spot”, the opposite screen section started to wash out and become noticeably brighter in areas that should have been black.

The same effect was seen watching nighttime scenes from CSI and Flash Forward – and it was very distracting. With most LCD TVs, as your viewing angle shifts off-axis, the entire screen starts to wash out. Instead, on the VF551XVT, you’ll see “hot” corners, sides, or large portions of the screen as you move slightly off-axis.

To me, that is a major problem as not everyone gets to sit in the best seat in the house. And the best seat has a small viewing “sweet spot” of about 30 degrees. Move beyond that, and you’ll clearly see the changes in black and low gray levels – something you will never see on a plasma TV. (Too bad Vizio stopped selling those!)

I’ll conclude my test bench results by stating that the VF551XVT produces a color gamut that is somewhat larger than the BT.709 standard HDTV gamut, with blue, red, and green all oversaturated. Color management tools would help pull these color points back in and more closely match the desired coordinates, as seen in Figure 6.

Figure 6. The plotted color gamut of the VF551XVT, compared to the BT.709 standard.

IMAGE QUALITY

This TV produces extremely sharp images that are rich in detail, no matter whether you are looking at a Blu-ray disc or an over-the-air broadcast. I selected scenes from Mission Impossible III to evaluate the judder-correction circuits and also to look at low-level image detail. For motion blur, I watched the Cowboys-Eagles Sunday Night Football game, carried over the air in the 1080i HD format from NBC stations WNBC-DT in New York and WCAU-DT in Philadelphia.

MI III is a great BD for crunch-testing deinterlacing circuits. Start with the Vatican reception scene in Chapter 8 and that famous shot of the camera zooming back as it pans down the closely-spaced stairs; a shot that drives deinterlacing circuits crazy. The VF551XVT handled it with ease.

Turning on the TV’s Smooth Motion processor will reduce the film judder to zero, producing more of a live video feel than film. Vizio’s blur reduction approach is more effective than any 120Hz correction circuits I’ve seen to date, but not as detailed as the few 240Hz processors I’ve checked out. Is this good? Bad? Depends on how much of a film purist you are.

The subsequent kidnapping of bad guy Philip Seymour Hoffman and the destruction of the Lamborghini looked spectacular. But the underground scenes lacked detail in dark areas, a direct consequence of those high black levels. Once again, moving ever-so-slightly in my seat resulted in the washed-out screen effect, which is as distracting to me as DLP color wheel breakup artifacts.

Figures 7a-b. These photos clearly show the off-axis brightness uniformity problem as seen from two different angles.

The football game fared much better (unless you are an Eagles fan), as the average picture level was above middle gray even in the darkest areas. I paid particular attention to close-ups of moving players as the sideline camera panned with them across a busy background. Not only is this an image blurring challenge, you’re also likely to see MPEG blocking artifacts (I did) which are just as much a challenge to filter out without softening the image.

The VF551XVT did a good job here in preserving image detail. Just a slight amount of blur was seen on the tightest shots and fastest zooms, some of which probably originated in the camera itself. So the 240Hz circuit works. It’s still not as crisp as a plasma display, but a big improvement over all of the 120Hz processors I’ve tested.

On the other hand, go lightly on the MPEG noise reduction as it does soften the image slightly. MPEG noise is difficult to eliminate completely – it’s embedded in the digital signal and the only way to minimize it is through expensive, powerful image processing, or through low-cost, high frequency filtering. That’s the approach you’ll find in this TV.

CONCLUSIONS

There’s no question about it – for $2,200, you get a lot of TV with plenty of inputs and calibration options. All Vizio TVs are ‘plug and play’ and you can turn it on and start watching with minimal adjustment. Five HDMI ports may be more than you’ll ever need, but where’s the Ethernet connection for Internet video viewing? (Better yet, where’s the wireless Ethernet hookup?)

While the VF551XVT is a nice job by Vizio in most respects, the off-axis image washout was a real turnoff. You’d never see this problem on a plasma TV, and it reminded me of watching rear-projection TVs – you had to sit right in the center to get the best image quality. Keep that in mind before you decide to buy one.

Power consumption: The VF551XVT operated for four hours in Standard mode with the backlight set to 50, displaying widescreen and HD broadcast content. Average power consumption during that time was 169.1 watts.

This entry was posted on Monday, January 11th, 2010 at 7:52 PM and is filed under Product Reviews.
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